Betis won 3-0 to reach the Europa Conference League group phase 5-0 on aggregate. Eze Abde (2) and Aitor Rubial struck for Betis.
Pellegrini later said: "The most important thing was to qualify for the group stage. We took an important step in the first leg and that was confirmed in the return leg. We need a good squad to go as far as possible in all three competitions. The first objective is to get past the group stage."
"I'm happy for the players who have had good individual performances. I'm also happy for Rodri, Iker Losada, Altimira... The way to put pressure on is to perform like today's. The squad has to perform in all competitions.
"What happened last year is now in the past. Things happened and this is a different season. We are thinking about qualifying for another group stage. We came in with a cool head, not thinking about the result we got there, and we achieved our goal."